Protective device.



E. E. F; GREiGHTO'N. PROTECTIVE DEVICE. APPLICATION FILED JULY 13, 1907.

1,099,590, Patented June 9,1914.

Translatifig Device MIN" .WZTAESSES'J JNYENTUH oscillations occur upon the conductor.

ELMER E. F. CREIGHTON, OF SCHENEGTADY, KEV? YORK, ASSIGNOR TO GENEEEL ELECTRIC CGMPANY, A GQR'PORATIDN OF NEXV PROTECTIVE DEVICE.

Specification of letters Fatent.

Applicatioh filed July 1a, 1902 Serial 1Io.383,636.

1 '0 all whom it may concern Be it known that I, ELDIER E. F. Guaran- ZION, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York have invented certain no and useful Improvements in Protective Devices. of which the following is a spezification.

My invention relates to protective devices for electric conductors and more particularly to devices which establish a. conducting establishes a conducting path to ground upon the occurrence on the conductor of a steady abnormal voltage or of oscillations of abnormal voltage and certain frequency. If oscillations of the, same voltage but of different, and particularly of higher frequency occur. a considerable period of time elapses before the dielectric between the electrodes breaks down, and during this time part of the high frequency oscillations may go to ground through the translating devices, but if inductance is placed in series With the spark gap to ground the time lag exhibited by the spark gap in the presence of high frequency oscillations is practically elimihated and the spark gap will break down almost instantly when very high iirequcncy Es:- perimcnts have demonstrated that oscillations of extremely high frequency encounter more dilficulty in breaking down an air gap than the oscillations of lower frequency produced by passing the extremely high i i-e quency oscillations through inductanccs con nected in series with the air gap.- If we gaps are connected in parallel, one having an inductance in series and the other having no inductance and both. are subjected to oscillations of the same high frequency, the gap in series with the inductance may be made more than twice as the gap without, inductance and yet the discharge yvill' always take place at the gap having inductance in series.

It has been proposed to relieve the conductor of very high frequency oscillations by using number of gaps in parallel; one having no inductance and the others having inductance in series therewith, but, this an ineliectivearrangement, because when very high frequency oscillations appear upon the conductor the park gap with no in ductance does break down quickly enough and while the other gaps break down almost instantly they do not p nit, free discharge a itcr they have broken down.

The object of my invention is to provide a. protective device between the conductor and ground arranged to act almost instantly upon the appearance of a voltage beyond a predetermined limit, regardless of the he quency of the oscillations of voltage, and establish. direct non-inductive conducting connection to ground to permit free discharge to relieve the conductor.

In carrying out my invention I connect the conductor to ground through two main e lectrodes separated by a spark gap or similar arrangement and provide a means cooperating with. the spark and responsive to h Y illations for ionizing and .i requency c. causing the break down. of the dielectric loci atonted June 1%,

tween the main electrodes thereby forming a direct. non inductivc path to ground. The

1116:1115 which I prefer to employ for this pinpose comprises an auxiliary electrode connected to the conductor through a. reactance or milar device for introducing inductance into the circuit and so arranged that when high frequency oscillations occur upon the conductor, a discharge instantly passes to ground from the auxiliary electrode. ionizing and puncturing the dielectric between the main electrodes and thereby instantly establishing a conducting path to ground to relieve the conductor of abnormal voltage. I

Other devices may be substituted for the air gap and other means responsiveto high I frequency oscillations may be substituted for the electrode connected through an inductance.

My invention will best he understood in connection with the accompanying drawings which are merely an illustration of one embodiment of my invention and in which Figure I is a diagrammatic view of a conduetorprovided with a protective device eml'mdving' my invention; and Fig; 2 1s a view of the device shown in Fig. 1 with part thereof omitted for the sake of clear- IIPSS.

in the drawings the conductor or line wire 1, which is to be protected, is connected through a reuctancc or similar device to the translating device 3 which may be a transformer, a generator, a motor, or similar device. The conductor 1 is connected to ground through an electrode at separated from a cooperating grounded electrode 5 by u spark gap, which breaks down when an abnormalvoltage occurs upon the conductor 1 and establishes a direct norrinductive circuit. hctiveen' the conductor 1 and ground through the clectnule at, the spark gap, and

the tech-ode 5, and instantly relieves the conductor '1 of the abnormal voltage.

ii a very high frequency oscillation occurs upon the conductor 1, the gap between the main electrodes 4 and 5 exhibits a pronounced time lag and requires such a length of time to break down that the insulation on the trinunatinp devices may he 'iuncturcd, and in order to avoid. this danger i provide means responsive to high frequency oscil- 'lations i'or causin the gap between the main electrodes 4- and o to break down instantly. The device which i prefer to use tor lhis purpoe comprises an auxiliary electrode 6, cl'mnccted to the conductor 'l and having an i nductance 10 in series therewith and so arranged that high frequency oscillations on the etmduclor will, instantly cause a dis charge from the electrode (3 througl'i the dielectric between the electrodes and 5, thereby ionizing and punctiliking;- the choice trio and estahlisning a direct non-inductive path between the conductor 1 and the ground it seems that the amount of the indiictance between the electrode 5 and the condu tor 1 determines the frequency of the oscillations which will instantly cause a discharge from the electrode, and in order to insure the l'n'euking down of the dielectric hetwceu the main electrodes la1 d 5, by oscillations of any :lrmmmcy, I provide any desired member of auxiliry electrodes, (3, 7, 8 and 9 cormecled to the conductor in series with inductances ll, ill, if: and 13, (littering from each other in amount and proportioned to "pond to oscillations of varying frequency, 7 that for instance oscillations of one frequency will cause a discharge throiiigh electrode 6, of another frequency will cause a, discharge tl'irough electrode 7, and 01": stiltanother frequenc will cause a discharge through electrode, 8.

The auxiliary electrodes a're arranged to insure that any discharge to ground from them will necessarily pass through the dielectric between the main electrodes l and to establish directnon-inductive path be- 'tween the conductor and ground, and the preferred arrangement is shown in Fig. 2 in which the electrodes 6 and 8 are separated from the main electrode 4- loy a very small air gap and are so positioned with relation to the electrode t that a discharge from either electrode (3 or 8 will go to the main electrode at and thence through the air gap to the main electrode 5, and thence to ground. t

In order to prevent the dynamo current forming, an arc across the gap between the electrodes & and 5, any siiitahlecurrent limiting device, preferably an aluminum cell 14, containing aluminum electrodes im' merscd in a suitable electrolyte, is connected between the electrode 5 and the round. My invention renders the Spark gap very sensitive to a great variety of abnormal conditions on the conductor, and iiistuutly relieves the conductor through the device i l. to ground without the formation of a destructive arc, so that the usefulness of lightning arresters consisting of a spark gap in series with a current limiting device is very greatly extended.

My invention may be embodied in many o1 her terms than that shown and described; l therefore do not desire to be restricted to the precise arrangement shown and aim to ('UW'I' by the appended claims all changes and modifications within the spirit and scope of my invention.

W hat l claim as new and desire to secure by Letters 'la tent of the United States, is,

1. In a protective device for electric conductors, the combination of a non-inductive low, resistance discharge path to ground. responsive to definite abnormal conditions on said conductor, and means comprising a plurality of circuits of difi'ering inductance responsive to a, wide range of other abnormal conditions for causing said discharge path to break down.

2. In a protective device for electric con-\lllfl mounted 'to cooperate with. the spark gap of said discharge path to cause said gap to break down.

3. In a prott .ive device for electric con-' ductors, the combination of a non-inductive spark discharge path containin a spark gap and responsive to definite con 1t10ns on sai conductor. and a. plurality of helices connected to said conductor in parallel with one an other, said helices forming with said spark gap a plurality of circuits differently ef- (main r In a prot ctwedewce for electric conductors, the combination with a main elec- 1,099,:seo

. fected by high frequency oscillations andrestfnonding to diiferent conditions on said conhctor to cause said spark gap to break down, whereby said discharge path is. rendered sensitive to a Wide range of abnormal conditions on said conductor.

4. In a rotective device for electric conductors, t e combination. of a main discharge path containing niain electrodes separated by a spark gap, and a plurality oi auxillar electrodes spaced away from said main e ectrodes to form auxiliary spark gaps which discharge to one of said main electrodes and thereby cause said main spark ga to break down, said auxiliary electrodes being connected to said conductor through inductive coils which render the circuits through the auxiliary electrodes responsive to high frequency oscillations and which difi'er from each other in amount, each of saidinductive coils having inductance renter than the inductance of said ischarge path.

trode connected to the conductor and arranged to form a non-inductive path to ground during a discharge from said electrode, of an auxiliary electrode-having inductance in series therewith connected to said conductor and spaced away from said inain electrode to form an auxiliary spark gap in a circuit which is responsive to high ,through said auxiliary oscillations and discharges gap tor p ground through said first electrode.

6. In a protective device for electric conductors, the combination with a vmain electrode connected to the conductor and arranged to provide a non-inductive path to ground through a dielectric, of a plurality of resonating circuits which respond to high Frequency oscillations, auxiliary electrodes having differing inductances in series therewith connected to the conductor and cooperating through spark 'ga s with the main electrode to ionize said ielectric and thereby establish a conducting path to ground through said main electrode.

7. In a protective device for electric conductors, the combination with a main electrode connected to the conductor and forming a discharge path to ground through a main spark gap, of a plurality of resonating circuits each comprising,an auxiliary electrode connected to the conductor through diii'ering amounts of inductance, and cooperating with the main electrode. through a spark gap of different length but each shorter'than said main spark gap.

In Witness whereof, I have hereunto set my hand this 12th day of July, 1907.

ELMER E. F. CREIGHTON.

Witnesses:

BENJAMIN B. HULL, HELEN Onronn.

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